TYPICAL POURING TEMPERATURE – A typical temperature for sand and chill
castings is 725°C but in practice it may range considerably above or below
this value, according to the dimensions of the casting.

Pouring temperatures for diecastings depend very largely on the
particular casting and the machine, and vary too widely for a typical
temperature to provide useful guidance. The melt should not, however, be
allowed to stand at temperatures only little above the freezing range or
the bottom of the melt may become enriched in such elements as iron and
manganese.

PATTERNMAKERS’ SHRINKAGE – 1.3% or 1/75 NB. For diecastings the
shrinkage may be expected to be considerably less.

Heat
Treatment

Ductility can be improved slightly be heating at 250-300°C, but apart
from stress relieving the heat treatment of LM6 is of little industrial
interest.

Applications and
General Notes

Suitable for marine ‘on deck’ castings, water-cooled manifolds and
jackets, motor-car and road transport fittings; thin sections and intricate
castings such as motor housings, meter cases and switch-boxes; for very
large castings, e.g. cast doors and panels where ease of casting is
essential; for chemical and dye industry castings, e.g. pump parts; for
paint industry and food and domestic castings. In general use where marine
atmospheres or service conditions make corrosion resistance a matter of
major importance. Especially suitable for castings that are to be welded.
The ductility of LM6 alloy enables castings to be easily rectified or even
modified in shape, e.g. simple components maybe cast straight and later
bent to the required contour – equally adaptable for sand and permanent
mould castings and for diecastings.

The aluminium-silicon alloys possess exceptional casting
characteristics, which enable them to be used to produce intricate castings
of thick and thin sections. Fluidity and freedom from hot-tearing increase
with silicon content and are excellent throughout the range. Their
resistance to corrosion is very good, but special care is required in
machining. In general, the binary alloys are not heat-treated; at elevated
temperatures their strength falls rapidly.

Although of medium strength, their hardness and elastic limit are low
but they possess excellent ductility.